(a) Field of the Invention
The present invention relates to a power factor correction circuit and a method of driving the same.
(b) Description of the Related Art
A power factor denotes the efficiency of power transfer. In power transfer, power that is actually transferred is real power. The power factor is obtained by dividing the real power by an apparent power represented by the product of effective values of voltage and current of power. Here, if both the voltage and the current have a sine wave, the power factor changes according to a difference in phase between the voltage and the current. As the difference in the phase decreases, the power factor is improved. Accordingly, in general, power factor correction for improving the power factor refers to an operation for decreasing the difference in the phase between the voltage and the current of power.
A conventional power factor correction circuit is configured to generate a voltage signal by performing full-wave rectification on an input AC power source and then generate an inductor current having almost the same phase and frequency as the voltage signal. To this end, the power factor correction circuit controls the switching operation of a switch connected to the inductor in order to control the inductor current. The inductor is electrically connected to the switch. When the switch is turned on, the inductor current and the switching current are identical to each other. Accordingly, when the switch is turned on, the power factor correction circuit measures a current flowing through the switch and controls the switching operation of the switching based on the measured current. In more detail, the power factor correction circuit compares a current flowing through the switch and a reference signal corresponding to a full-wave rectified voltage, and controls the switching operation of the switch based on the comparison results. Since the reference signal varies depending on the full-wave rectified voltage, the current flowing through the switch element varies depending on the reference signal. Accordingly, the inductor current varies depending on the full-wave rectified voltage, so it has almost the same phase and frequency as the voltage and current of the input AC power source.
Here, the conventional power factor correction circuit uses a resistor element for detecting the full-wave rectified voltage and generating the reference signal based on the detected voltage. The full-wave rectified voltage is chiefly high, and it is difficult to integrate a resistor element that withstands a high voltage. Accordingly, a problem arises because it is difficult to integrate the power factor correction circuit. Further, additional power consumption is generated in the resistor element.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.